Process for purifying petroleum crude oils

ABSTRACT

The invention relates to removing contaminants from oil using solid sorbents that are comprised primarily of carbon and preferably of coke particles. The coke particles have an affinity for contaminants in oil and are sized to be filtered from oil without plugging. Most contaminants have such a small size that they tend to plug up filters. As the contaminants agglomerate onto the solid sorbent, the resulting particles form a filter cake on conventional filter materials in such a way as to allow the oil to pass on through without significant pressure drop or delay.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims benefitunder 35 USC §119(e) to U.S. Provisional Application Ser. No. 62/093,576filed Dec. 18, 2014, entitled “Sorbents for Removing Solid Particlesfrom Crude Oil”, to U.S. Provisional Application Ser. No. 62/093,668filed Dec. 18, 2014, entitled “A Mixture of Crude Oil and SolidHydrocarbon Particles”, to U.S. Provisional Application Ser. No.62/093,690 filed Dec. 18, 2014, entitled “A Mixture of Crude Oil andSolid Hydrocarbon Particles”, to U.S. Provisional Application Ser. No.62/093,708 filed Dec. 18, 2014, entitled “A System for Purifying CrudeOils”, to U.S. Provisional Application Ser. No. 62/093,722 filed Dec.18, 2014, entitled “A System for Regenerating Adsorbents for PurifyingCrude Oils”, to U.S. Provisional Application Ser. No. 62/093,797 filedDec. 18, 2014, entitled “Upgrading Biofuel Crude Oils with SolidSorbents for Petroleum Refinery Processing”, and to U.S. ProvisionalApplication Ser. No. 62/093,832 filed Dec. 18, 2014, entitled “A Processfor Purifying Petroleum Crude Oils”, all of which are incorporatedherein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

This invention relates to removing salts and other matter from raw crudeoil prior to refining the crude oil and especially to systems andprocesses for capturing salts and other solid material contaminants thatmight cause corrosion or fouling within refinery systems.

BACKGROUND OF THE INVENTION

Raw crude oil generally contains undesirable impurities includinginorganic and organic solids, salts, water droplets, unstable largepolar molecules etc. which are the root causes for various fouling onprocessing equipment in refinery production. Equipment fouling isbroadly defined as reduced production efficiency such as reducedthroughput because of solid deposition on liquid transfer pipes andincreased energy consumption because of reduced thermal transferefficiency through thermal process walls. Equipment fouling due to theprecipitation of the undesirable materials occur at various processingstages in petroleum refineries such as crude hot train exchanger,atmospheric towers, vacuum furnace and vacuum tower, coker furnaces, andhydro and thermal cracking units, results in substantial efficiencylosses. It is desirable to remove these undesirable materials in crudeoil before the crude oil is put through the subsequent thermalprocesses.

Inorganic salts typically include various metal chlorides, sulfides, andoxides etc. such as calcium, sodium and magnesium chlorides and otherparticulates. Salts cause corrosion in refinery systems that areexpensive to repair and require more frequent shutdown and longerturn-around before profitable operation resumes. Corrosion is causedprimarily by hydrochloric acid (produced from the hydrolysis of salts athigh temperatures) in crude oil distillation columns and overheadsystems. Since salts in crude oils are a significant problem andconcern, removing such salts is an important operational process in arefinery.

Typically, desalting crude oil involves adding water to the incomingcrude oil emulsifying the water and oil by shearing across a globevalve, which is also known as a mix-valve and allowing the oil and waterto separate in a desalter settling vessel. The salt preferentially andfairly rapidly dissolves into the water immediately following themix-valve so the remaining step is to separate the water from the oil.The oil and water are separated based on their density differences.Desalted crude exits from the top of the desalter settling vessel to thecrude distillation tower while effluent water or brine exits from thebottom. However, desalting heavy crude oil in a refinery desalter systemis challenging due to the relatively high viscosity of heavy crude andrelatively high densities of heavy crude oil relative to the water withthe captured salt. Moreover, water and oil emulsions for heavy crude oiltend to be more stable than for light oil and stable emulsions makedesalting less successful or at least more difficult.

Because of the chemical incompatibility of crude oil, organic solids,and water, the separation of crude oil and water emulsions in many casesdoes not remove impurity solids into the water phase from crude oil.With extreme variation of chemical constituents of crude oils, there isnot a universal demulsifier for crude oil/water emulsions to helpprovide for oil/water separation. Existing desalting processes are notonly inefficient for removing undesirable impurities in crude oil, theymay also create additional undesirable waste such as stable crudeoil/water emulsions and increased solid and water content in crude oil.In addition, current desalting processes use a large amount of freshwater (>4% based on crude oil) and chemicals such as demulsifiers andwetting agents etc., such that the resulting water contains dissolvedsalts, oil droplets, and other organic solids. Disposing suchcontaminated water adds significant cost to the desalting process.

It has been known in the refinery industry that specific foulingproblems such as those at atmospheric and coker furnaces can bemitigated by removing organic solid and inorganic solids in crude oiland feed heavy oil. However, there is not any practical process toremove such solids from crude oil. Even at a laboratory scale, removingsuch solids by filtration is not practically feasible because the solidsin crude oil would clog up the filter quickly as the solids in crude oilexist in colloidal particles coated with sticky organic compounds. Thereis no known practical method to remove organic solids in crude oils.

Some crude oils contain large and polar compounds which are inherentlyunstable in the crude oils. When such crude oil comes into contact withthe wall of processing equipment, such as in an atmospheric or cokerfurnace, those compounds tend to precipitate out forming a thermallyinsulating layer on the wall and resulting in a drastic reduction inthermal transfer efficiency. There is not any known practical process toremove these large unstable compounds to prevent such equipment fouling.

Any improvement to removing impurities from crude oil would be verydesirable for refineries.

BRIEF SUMMARY OF THE DISCLOSURE

The invention more particularly relates to a process for removingcontaminants and basic or alkaline species contaminants from crude oil.A solid sorbent is added to crude oil where at least some of the solidsorbent has been partially oxidized. Solid contaminants areagglomerated/adsorbed from the crude oil onto the solid sorbent whereinbasic or alkaline species contaminants are also adsorbed to the oxidizedsolid sorbent. The solid sorbent with agglomerated contaminants is thenseparated from the crude oil.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1 is a schematic drawing of a first embodiment of process forremoving contaminants from oil;

FIG. 2 is a schematic drawing of a second embodiment of the process ofseparating contaminants of oil;

FIG. 3 is a schematic drawing of a third embodiment of a process forseparating contaminants of oil including a system for activating thesolid sorbent to have an affinity for basic species contaminants;

FIG. 4 is a schematic drawing of a fourth embodiment of a process forseparating contaminants of oil including a system for activating thesolid sorbent to have an affinity for basic species contaminants.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow.

The present invention relates to the discovery of using particulategreen coke as a solid sorbent for impurities in crude oil. Solidsorbents eliminate the challenging problem of current technologies ofusing highly dispersed water to collect salts in crude where the wateris so highly dispersed that it is a challenge to then separate the waterback from the crude. The solid sorbents of the present invention aresized to be easily separated from crude oil by filtration.

Crude oil commonly includes contaminants and other undesirable materialsthat cause problems for refineries. These contaminants come in manyvarieties including organic and non-organic solids, salt containingwater droplets, and large polar molecules that are inherently unstablein the liquid phase at treatment temperatures within a refinery. Thoseunstable compounds tend to preferably precipitate out to form solidswhen they come to contact with equipment surface on the processequipment. The solid particulates tend to be quite small or fineoccurring at about one micron and typically much less. To the extentthat one might try to separate these contaminants by filtration, thefilter element would have to be an exceptionally fine mesh. Such a finemesh is quite vulnerable to plugging creating an unacceptably highpressure drop and slow flow rate through such filters. Othercontaminants have an organic nature and are suspended in the crude oilforming a colloid. Some contaminants include inorganic solid particleswith organic molecules on the surface.

Through many years of research on organic and pitch chemistry,particularly related to the precipitation of pitch solid particles inpitch-organic solvent systems, the inventor discovered that some solidparticles such as green coke particles exhibit the ability toeffectively absorb ultrafine organic particle along with unstable largecompounds. The resulting solid particles can be easily separated fromthe liquid by filtration. This invention provides an effective methodfor the simultaneous removal of organic and inorganic solids, salts,undesirable compounds in crude oil with solid particles.

Green coke, as a surface/sorbent, is chemically similar to the impuritysolid particles and unstable compounds in the crude oil. As such, ittends to agglomerate with and adsorb these organic contaminants forminglarger particles. These particles also tend to capture water dropletsand thereby gather the salt as the water droplet in crude oils aretypically covered with large polar molecules, which is akin to thesurface of sorbent and adsorbed particles. These now larger particles,especially considering that they have the underlying size andconsistency of the coke, are amenable to being removed from the crudeoil by filtration having a mesh that allows relatively high flow rates.Once filtered, the crude oil has been found to have significantlydiminished amounts of contaminants.

The green coke particles that are mixed in to the crude to capturecontaminants are sized or selected having an average particle size of atleast 1 micron up to about 250 microns, with particles being between 5and 50 microns being more preferred. The green coke is mixed into theraw crude oil and thoroughly dispersed to provide for as much contactwith contaminates as can be efficiently accomplished.

As shown in FIG. 1, the crude oil is directly to a mixing tank 12 from asupply line 15. The solid sorbent is added at delivery station 18 andthe mixture of raw crude oil and solid sorbent is blended by agitator20. The mixture of crude oil having the solid sorbent thoroughlydispersed therein is then separated by filter element 22 allowing theecontaminated crude to pass through outlet 25 while wet solid sorbentwith agglomerated contaminants thereon are allowed out throughcontaminant outlet 28.

It should be understood that a number of embodiments for the inventivesystem may be defined such as shown in FIG. 2 where a section of pipe 32for transporting crude oil includes an inlet 38 for sorbent. The sorbentis blended and dispersed through the crude oil via a static mixer 41. Afilter element 42 is positioned at the end of the pipe section 32defining a crude outlet 45 and a contaminant outlet 48. The pipe section32 may be horizontal, vertical with the flow going up or down or anyother angle. The filter element 42 may be perpendicular to the flow ofthe oil through the pipe section 32, perpendicular to the pipe section32 (such as in the side walls) or any other practical orientation in thepipe section 32. Similarly, the contaminant outlet may also be arrangedat an angle to the pipe section or straight out the end.

The crude oil mixture comprises between 95% and 99.9% crude oil andbetween 0.05% and 5% green petroleum coke solid sorbent. The greenpetroleum coke solid sorbent has an average size between about 2 micronsand about 50 microns although sizes between about 5 microns and about 15are generally preferred. The mass ratio of crude oil to sorbent may bemaintained at a ratio of at least 1 kg sorbent to 500 kg of crude oil.More preferably, the crude oil would include a higher ratio of sorbentsuch that at least 5 kg of sorbent would be thoroughly mixed with 500 kgof crude oil such that the ratio is 100:1. The ratio may include up to 1kg of sorbent to 2 kg of crude oil when the crude oil is heavily ladenwith contaminants, but as a practical matter, it is more likely that theratio will be between 100:1 and 10:1. The composition may be maintainedat a temperature that is elevated above average room temperature butless than 200° C.

The density of the sorbent is preferably between 0.5 g/cc and 7 g/cc andmore preferably between 0.7 g/cc and 2.0 g/cc. The sorbent particles arepartially or almost totally hydrocarbon materials that contain aresidual carbon content of at least 40%, preferably between 75% and 99%,more preferably between 85% and 98%. The residual carbon content isdefined by ASTM D7662-13. The average particle size of the sorbent isbetween 1 and 500 micron, preferably between 1 and 50 micron, and morepreferably between 3 and 50 micron.

The wet green coke with the agglomerated/adsorbed contaminants may beprocessed for re-use. As shown in FIG. 3, a mixing tank 112 is providedfor mixing crude oil and solid adsorbent. Crude oil is supplied at inlet115 and fresh adsorbent is supplied at inlet 118. After mixing using asuitable mixing technology, the mixture is conveyed via line 119 toseparation device 120 including filter media 122. While one separationdevice 120 is shown, it should be understood that multiple such devicesmay be included where some are in use having a filter cake formed on themedia 122 while other separation devices 120 are offline having thefilter cake flushed or back-flushed for further treatment. The cleanedcrude oil is removed through outlet 125 and carried on for furtherprocessing in the refinery and the crude laden adsorbent exits via line128. The sorbent is subjected to further separation at sorbent separator151. Some solid sorbent 152 is returned to the mixing tank 112 whileremaining sorbent with crude is delivered to regenerator 161 via line153. While the amount of crude with the sorbent in sorbent regenerator161 is small compared to the crude recovered at outlet 125, clean crudeis discharged through outlet 162 and directed for further processing inthe refinery. Solid waste is discharged via outlet 163 which ispreferably disposed on continuous basis. The re-generation processincludes recovery of liquid oil and thermal treatment of the solidmaterial to liberate or pyrolize the contaminants. The wet sorbent afteradsorption first goes through evaporation to recover the liquid oil atan elevated temperature either under reduced atmosphere pressure or atambient pressure. The dried solid powder is subjected to the specificthermal treatment either under reduced atmosphere pressure or at apressure less than 15 psi. The sorbent is subjected to regeneratingtemperatures that are at least 100° C., preferably between 100° C. and1000° C., more preferably between 200° C. and 750° C., even morepreferably between 250° C. and 550° C. The atmosphere for the thermaltreatment is preferably inert; nitrogen gas and other hydrocarbon gasare preferred.

Regenerated green coke sorbent is delivered to the mixing tank 112 vialine 164 and 171. It is noted that a device 170 is shown for providingan alternative treatment for the sorbent as will be described below. Theregenerated coke sorbent attains substantial amounts of its sorbentfunctionality through regeneration, but the step typically includes someselection by sizing eliminating sorbent particles that have attritteddown to an unacceptable size and eliminated from the process throughdischarge 163. Using recycled sorbent is a low cost way to reuse sorbentthat provides some level of sorbent function, but especially helps byincreasing the available surface area within the crude mixing tank so asto create many contact opportunities by the sorbent and thecontaminants.

The process may further be accomplished with a system having a differentappearance but similar operations as shown in FIG. 4 where the crude oilenters a mixing area 232 via inlet 215. Fresh green coke sorbent isdelivered via inlet 218. The sorbent and crude oil are mixed together bya mixer 241, such as a static mixing element as shown. The cleaned ordecontaminated crude exits through outlet 225 after passing throughfilter media 222. The crude laden sorbent is carried on through line 228for further separation at sorbent separator 251. Some solid sorbent 252is returned to the mixing zone 232 while remaining sorbent with crude isdelivered to regenerator 261 via line 253. While the amount of crudewith the sorbent in sorbent regenerator 261 is small compared to thecrude recovered at outlet 225, clean crude is discharged through outlet262 and directed for further processing the refinery. The re-generationprocess includes recovery of liquid oil and thermal treatment of thesolid material. The wet sorbent after adsorption first goes throughevaporation to recover the liquid oil at an elevated temperature eitherunder reduced atmosphere pressure or at ambient pressure. Regeneratedgreen coke sorbent is delivered to the mixing zone 232 via line 264 and271. Device 270 provides an optional treatment for the sorbent asdescribed below. The regenerated coke sorbent attains substantialamounts of its sorbent functionality through regeneration, but the steptypically includes some selection by sizing eliminating sorbentparticles that have attritted down to an unacceptable size andeliminated from the process through discharge 263.

EXAMPLE 1

As an example of this process, two common crude oils were mixed togetherusing 180 grams of WCS (West Canadian Sour)) crude oil and 120 grams ofBakken crude oil were mixed together to form a mixture and then splitinto two. A 150 gram sample of the mixture was mixed with 3 grams of agreen coke powder in a 500 ml Erlenmeyer flask on a hot plate with amagnetic bar. After the mixture temperature reached 70° C., the mixturewas poured into a filtration flask (9 cm in diameter) and filteredthrough a 0.45 μm Nylon filter membrane. The filtrate was collected assolid-removed crude oil blend. The filtration cake was washed thoroughlywith toluene, dried under Vacuum at 110° C. The dried powder was usedagain with the other 150 grams of the crude oil blend in the same way asthe first time. The same filter membrane in the first time was used inthe second filtration. The final dried solid powder weighed 3.21 grams,gaining the total solid weight of 0.21 grams, or 700 ppm based on thecrude oil blend.

The green coke powder used in this experiment has an average particlesize of 8 μm and the carbon content of 93%. Its weight does not changemuch through above crude oil soaking and toluene washing processes. Thecrude oil blend contained 350 ppm of so-called filterable solid asdetermined by standard toluene dilution and washing procedure. Thus, thegreen coke powder adsorbed more than “solvent filterable solid”.

The filtration speed was fast in both the filtrations; particularlythere was apparently not any filtration resistance at washing andfiltering step, indicating that the filter membrane was not clogged byany solid even after two filtration and that all the solid particlesfrom the crude oil blend were adsorbed on the green coke sorbents. Incomparison, the crude oil couldn't be directly filtered through themembrane under the same condition; the filter membrane was completelyclogged up after a few minutes.

A sample of 186 grams of the filtered crude oil was mixed with 14 gramof deionized water and the mixture was heated to 70° C. and then blendedwith 20 ppm of a demulsifier in a Waring® blender at 8000 rpm for 16seconds. The resulting emulsion was poured into two portableelectrostatic desalter tubes, and 600 volts (DC) was applied toaccelerate dehydration of the emulsion. For comparison, the same crudeoil blend without the above filtration was subjected to the sameprocess. After 90 minutes, the voltage was turned off and the tubes werevisually examined to determine the dehydration condition. These tubeswere placed in a centrifuge and spun at 16000 rpm for 20 minutes so thatwater and crude oil was completely separated. A sample of 5 ml of thedesalted water was taken from each tube and diluted with 50 ml ofdeionized water and the ionic conductivity of the diluted water sampleswas measured with an ionic conductivity meter.

After 90 minutes of electrostatic desalting and centrifuge, theinventive sample was clear while the conventional sample was cloudy.Even though all the water has apparently been separated out for both thecases, there is a big particle cloud suspending between water and oillayers in the case with the crude oil whereas the separation betweenwater and crude oil is very clear in the case with the solid removedcrude oil. On the other hand, the ionic conductivity of the DI deionizedwater, the desalted water from the crude oil that from the solid-removedcrude oil was 64, 91, and 777 μS, respectively. As the ionicconductivity value reflects the total salt concentration in the desaltedwater; the remaining salt in the solid removed crude oil is about 4% ofthe original content ((91−64)/(777−64)*100).

It is been demonstrated that green coke particles in this case actuallyalso adsorbed ultrafine water droplets in the crude oil because thesewater droplets are typically coated with large and polar molecules thatare really akin to polar coke surfaces.

EXAMPLE 2

A sample of 250 grams of a light crude oil from a refinery desaltingunit were mixed with 5 grams of a green coke powder in a 500 mlErlenmeyer flask on a hot plate with a magnetic bar. The green cokepowder has an average particle size of 8 μm and a residual carboncontent of 89%. After the mixture temperature reached 70° C., themixture was poured into a filtration vessel (2¼ inch in diameter) andfiltered through a 0.5 μm sintered stainless steel disk under a pressureof 80 psi. The filtrate was collected as purified crude oil. Thefiltration cake was washed thoroughly with toluene and dried undervacuum at 100° C. for 14 hours. The water content and inorganic elementsin the crude oils before and after adsorption/filtration were analyzedto determine the removal effectiveness of the contaminants. Forcomparison, the crude oil after desalting at the same refinery unit wasalso analyzed. The analytical results are given in Table 1 and 2

EXAMPLE 3

The experiment in Example 2 was repeated with the crude oil that hadbeen desalted from the same refinery desalting unit.

EXAMPLE 4 AND 5

These two examples are similar experiments to Example 2 and 3 and wereconducted with a heavy crude oil from a different refinery unit. Theanalytical results are also listed in Table 1 and 2 for comparison.

It is worth pointing out here that the commercial desalting unit usedabout 6% water based on the total crude oil, which generating a wastestream of at least 6% of the total crude. For the solid sorbentadsorption process, there is not any waste generated because thecontaminant-loaded sorbent can be re-used after a simple heat-treatmentand the contaminant-loaded sorbent still contains at least 40% carbonand has a heating value similar to fuel grade coke. As compared inTables 1 and 2, the solid adsorption/filtration has the followingadvantages over conventional desalting processes: a) it does not usewater, b) it removes more salts and solids than desalting, and, c) itremoves more water content from crude oils than desalting.

The above examples have elucidated the fundamental features of thisinvention: a) green coke powder is used as the sorbent to adsorbcolloidal organic and inorganic particles including ultrafine waterdroplets from crude oils, b) the resulted solid particles and cleanedliquid crude oil can be easily separated continuously, c) the resultedcrude oils from the process is super clean in the terms of organic andinorganic solid particles and salts.

TABLE 1 Water Total Solid Crude Sample API Content (ppm) removed (ppm) 1Raw 40.5 1114 Desalted 38.7 622 Adsorbed 39.0 209 420 Desalted &Adsorbed 38.0 207 240 2 Raw 15.9 4644 Desalted 15.8 5910 Adsorbed 16.61193 380 Desalted & Adsorbed 16.7 1498 273

TABLE 2 IC and ICP measurable elements in crude oil (ppm) Crude SampleCl Al Ca Fe Mg Na Ni V Raw 56.5 1.93 5.66 10.1 Not 18 2.28 4.46 Desalted1.7 <1.07 1.01 4.45 Measurable <7.89 <2.24 4.44 Adsorbed 0.6 <1.02 0.727<3.17 <7.57 <2.15 4.29 Desalted & 0.3 <1.02 1.0 <3.17 <7.56 <2.15 4.38Adsorbed Raw 50.7 1.89 22.3 5.35 1.84 35.4 70.8 287 Desalted 5.3 <1.035.68 <3.20 <1.34 <7.65 70.8 289 Adsorbed 3.0 <0.996 6.51 <3.09 <1.30<7.37 71.7 294 Desalted & 2.8 <1.03 2.92 <3.19 <1.34 <7.61 72.9 301Adsorbed

Some crude oils contain corrosive compounds such as various amines.These species are typically soluble in crude oil, but they would formamine salts with chloride during refinery processing, causing severecorrosion on the refinery equipment. With the solid adsorption process,these soluble basic species may also be effectively removed from crudeoil by including an acidifying treatment to the green coke sorbent. Thisacidifying treatment may be applied in device 170 or 270 as shown inFIGS. 3 and 4. For the applications where basic species such as aminesneed to be removed, the atmosphere is preferably oxidative; oxygen gasand other oxidative gases such as various acids and peroxides are alsointroduced into the atmosphere so that carbonaceous species on thesorbent surface are oxidized to form acidic groups. These acidic groupson the sorbent surface provide the functionality of absorbing basicspecies such as amines from crude oils. The acidifying regenerating stepwould be performed in the regenerator 161.

With a blend of fresh green coke and acidified green coke particles, thesame materials being adsorbed/agglomerated as first described are stillbeing adsorbed and agglomerated, but there are now sorbent particlesthat also adsorb the basic or alkaline molecules, such as amines.

Examples showing the enhanced benefit of this aspect of the inventioninclude:

EXAMPLE 6

200 grams of Albian synthetic heavy crude oil were mixed with 4 grams ofa green coke powder in a 500 ml Erlenmeyer flask on a hot plate with amagnetic bar. After the mixture temperature reached 80° C., the mixturewas poured into a filtration vessel (2¼ in diameter) and filteredthrough a 0.5 μm sintered stainless steel disk under a pressure of 80psi. The filtrate was collected as purified crude oil. The filtrationcake was washed thoroughly with toluene and dried under vacuum at 100°C. for 14 hours. The dried powder weighed 4.2176 grams, yielding thetotal solid particle and salt content of 0.2176 grams or 1 088 ppm ofthe crude oil.

The solid powder was transferred into a ceramic crucible, placed in atube furnace, and heated under nitrogen gas atmosphere at 450° C. forthree hours. The weight of the solid powder was measured before andafter the heating, yielding a loss of 39% based on the adsorbed solidparticles.

The crude oils and the solid powders before and after adsorption wereanalyzed for their elemental compositions with Inductively CoupledPlasma Atomic Emission Spectroscopy and water content by Karl Fischertitration. Table 3 shows comparison of the compositions.

EXAMPLE 7

Example 6 was repeated with the used and heat-treated sorbent fromExample 6. The weight gain on the solid sorbent showed that 1070 ppm ofthe solid particles were removed by the adsorption from the crude oil inthis case. The solid powder was again subjected to the same heattreatment as Example 6. The elemental compositions and water content ofthe purified crude oil are also given in Table 3 for comparison.

EXAMPLE 8

After Example 7 was repeated three times with the same sorbent, insteadof washing residual crude oil from the wet solid cake with toluene, thewet solid cake was directly dried under vacuum at 100° C. for 15 hours,and then the dried solid powder was heated under the same condition asExample 1. Example 2 was then repeated using this solid powder. Theweight gain on the solid powder from the adsorption showed a solidremoval of 1091 ppm from the crude oil. The elemental composition andwater content of the purified crude oil is listed in Table 3.

As shown in Table 3, Except for Ca, Ni, and V, all the other detectableinorganic elements have been adsorbed and removed from the crude oil tobelow detectable level, even those undetectable elements are alsoclearly adsorbed and transferred on the solid sorbent. For Ca, Fe, andV, only a small portion was adsorbed by the solid sorbent, possiblybecause they exist in chelates in the crude oil. From the first fourcolumns, it can be easily calculated that the amounts of those elementsconcentrated on the solid sorbent are equal to the corresponding amountfrom the raw crude oil ((the 1st column−2nd column)×50=−(4^(th)column−3rd column)). Except for the first adsorption with fresh sorbent,the water content in the crude oil was also reduced after adsorption.The fresh green coke powder used in the first example might contain somemoisture because the sample has been stored at ambient condition formany years before use, resulting in addition of trace water.

COMPARATIVE EXAMPLE

A typical desalting experiment was conducted with the same crude oil inthis example for comparison. A sample of 2400 grams of the crude oilwere mixed with 20 ppm of the demulsifier (Nalco EC 2472A) and heated to90° C. and blended with 7% deionized water at 8000 rpm for 16 seconds.The resulting emulsion was pumped into/through a laboratoryelectrostatic desalter at a rate of about 700 grams per hour. A voltageof 1000 volts was applied to the grids of the desalter during desalting.However, there was not any separation between water and oil during theexperiment (about three hours). Thus, the crude oil could not bedesalted with the conventional method.

The above examples have elucidated the fundamental features of thisinvention: solid sorbents can be used effectively to adsorb solidparticles, salts, and water in crude oils and the consumed sorbent canbe regenerated by thermal treatment.

TABLE 3 Composition (Wt ppm) Example 1 Sorbent Example 2 Example 3 RawPurified Fresh coke after Purified Purified Element Crude Oil Crudesorbent adsorption Crude Crude Al 30.5 1.15 28.9 1710 <1.02 <1.03 B<5.19 <5.10 <5.27 <5.36 <5.21 <5.25 Ba <3.05 <3.00 4.87 14 <3.07 <3.09Ca 6.95 2.8 22.2 173 1.2 1.11 Cd <2.03 <2.00 <2.07 <2.10 <2.05 <2.06 Co<2.24 <2.20 <2.27 8.73 <2.25 <2.26 Cr <4.58 <4.50 <4.65 37.4 <4.60 <4.63Cu <1.12 <1.10 <1.14 3.57 <1.13 <1.13 Fe 59 <3.10 45.2 2780 <3.17 <3.19K <29.3 <28.8 <29.8 128 <29.4 <29.6 Li <1.12 <1.10 <1.14 1.2 <1.13 <1.13Mg 1.68 <1.30 4.75 87.4 <1.33 <1.34 Mn 1.16 <0.300 0.737 55.2 <0.307<0.309 Mo 12 <3.10 <3.20 438 <3.17 <3.19 Na <7.52 <7.40 14 233 <7.57<7.61 Ni 47.1 35.8 <2.17 548 36.3 35.7 P <7.12 <7.00 <7.23 28.7 <7.16<7.20 Sr <0.305 <0.300 <0.310 4.4 <0.307 <0.309 Ti 4.33 <2.10 3.39 126<2.15 <2.16 V 81.4 67.2 4.24 684 69.4 67.9 Zn 1.78 <0.400 <0.413 101<0.409 <0.411 Zr <1.53 <1.50 <1.55 3.56 <1.53 <1.54 H₂O 2006 2013 NotMeasured 1663 1595

The process is particularly applicable to removing solid particles andsalt-containing water droplets from bio-sourced oils or biofuel crudeoils. The solid sorbents are dispersed in crude oil such that solidsorbent particles and crude oil has sufficient contact, resulting infull adsorption of the solid particles (ultrafine and micron sizedorganic and inorganic solid material) in the crude oil. The resultingsolid sorbent and liquid crude oil is separated continuously orsemi-continuously through filtration. The details are described below.

Referring to FIG. 1, the process according to this invention includestwo simultaneous major steps: (a) mixing solid sorbent with crude oiland (b) separating impurity solid and salt particle-loaded sorbentparticles from liquid crude oil. The special sorbent materials accordingto this invention enable such operation to be effective and economicallyviable.

Green coke particles were found to be effective in adsorbing colloidalorganic and inorganic solid particles as well as ultra-fine waterdroplets in fossil crude oils (see the related IR). In this invention,green coke particles are also good at adsorbing the impurity solidparticles and water droplets in biofuel crude oil. The impurity solidand salts-adsorbed coke particles can be easily separated from liquidcrude oil by any mechanic method such as filtration and the resultingbiofuel crude oil is solid-free and can be directly processed intraditional refinery systems.

Even though conventional solid sorbents such as activated carbon orfiltration aid agent such as silicate and Celite® may be used as thesorbent for this purpose, green coke particles are preferred becausethose conventional sorbents are relatively expensive and may not havethe affinity with crude oil compared with particulate green cokematerials. The so called “green coke” materials herein are petroleumcokes or charred coal tars before calcination (>1000° C.) that contain acertain amount of volatile content. Preferably the green coke has carboncontent between 25% and 99.0%, more preferably between 75% and 98%. Theamount of volatile content in a green coke may reflect the mechanicstrength of green coke particles and the affinity of such coke surfacewith crude oil; a too high volatile content may lead to too weakmechanic strength of green coke particles, which may cause breaking-upof particles on collision of particles. A too high carbon content(e.g. >99.5%) may yield a low affinity with crude oils, which may have alow adsorption ability for large and polar molecules that are preferablyremoved from crude oil.

It should be pointed out here that the above sorbent or green cokematerials may also contain significant amount of inorganic solids, thecarbon content aforementioned is the hydrocarbon portion in the sorbent.

The size of green coke particles is important factor in determiningadsorption rate and maximum loading of adsorbed solid particles. Thesmaller the particle size the larger the surface area and the faster foradsorption. However, the smaller particle size also may lead to thedenser filtration cake layer on the filtration screen, resulting in aslower liquid flow rate. To achieve a fast adsorption rate and a goodliquid flow through the filtration screen, the average green cokeparticle size is preferably between 3 and 500 μm, more preferablybetween 5 and 50 μm.

Now, referring to FIG. 1 for the process, mixing and filtration issimultaneously conducted and the solution near the filter screen isagitated so that a thick filtration cake layer would not build on thefilter screen. Particle-loaded sorbent materials may be continuouslyremoved from the bottom section while fresh sorbent material is alsocontinuously added and mixed with incoming crude oil. Alternatively, twofilter tanks may be used sequentially; one is operated on filtrationmode while other one is operated on removing particle-loaded sorbentmaterial.

EXAMPLE 9

A sample of 60 grams of an algae biofuel crude were mixed with 1.55grams of a green coke powder in a 250 ml Erlenmeyer flask on a hot platewith a magnetic bar. After the mixture temperature reached 90° C., themixture was poured into a filtration vessel (2¼ inch in diameter) andfiltered through a 0.5 gm sintered stainless steel disk under a pressureof 80 psi. The filtrate was collected as purified algae crude oil. Thefiltration cake was washed thoroughly with toluene and dried undervacuum at 100° C. for 14 hours. The dried powder weighed 1.67 grams,yielding the total solid particle and salt content of 0.12 grams or 0.2%of the algae crude oil.

The element contents in the purified algae crude oil, the solid powder,and the substrate green coke powder were analyzed using an inductivelycoupled plasma atomic emission spectroscopy; a comparison of the resultsare given in Table 1. It can be seen that the inorganic elements such asAl, Ba, Ca, and P, etc. have been effectively removed from the liquidcrude, whereas only a small fraction of the elements such as Cu, Fe, Ni,and Zn were removed, possibly these transition metals exist as chelatedcompounds in the liquid.

The above example has elucidated the fundamental features of thisinvention: a) green coke powder is used as the sorbent to adsorb solidparticles and salts from biofuel crude oil, specifically algae crudeoils and b) the resulted solid particles and purified liquid crude oilcan be easily separated through filtration.

TABLE 4 Purified algae Filtration Green coke Sample crude oil solidpowder Elements Content by weight (ppm) Removed (%) Al <11.1 3710 28.999.2 B <5.26 <5.25 <5.27 Ba <3.10 47.3 4.87 89.7 Ca 50.7 5640 22.2 73.3Cd <2.06 <2.06 .07 Co <2.276 <2.26 <2.27 Cr <4.64 53.6 <4.65 100.0 Cu 1919.7 <1.14 2.5 Fe 1170 2440 45.2 4.9 K 53.6 1660 <29.8 43.6 Li <1.14 2.5<1.14 100.0 Mg 32.9 1800 4.75 57.6 Mn 4.82 131 0.737 40.2 Mo <3.20 12.5<3.20 100.0 Na 181 955 14 11.5 Ni 31.2 74.2 <2.17 5.6 P 15.4 3840 <7.2386.2 Sr <0.310 71.7 <0.310 100.0 Ti <2.17 172 3.39 98.0 V <4.23 8.67<4.24 100.0 Zn 52.9 87.4 <0.413 4.0 Zr <1.55 5.76 <1.55 100.0

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as an additional embodiment of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

1. A process for removing contaminants and basic or alkaline speciescontaminants from crude oil comprising: a) adding a solid sorbent tocrude oil where at least some of the solid sorbent has been partiallyoxidized; b) agglomerating/adsorbing solid contaminants from the crudeoil to the solid sorbent wherein basic or alkaline species contaminantsare also adsorbed to the oxidized solid sorbent; and c) separating thesolid sorbent with agglomerated contaminants from the crude oil.
 2. Theprocess according to claim 1 wherein the solid sorbent is solidhydrocarbon material.
 3. The process according to claim 2, the solidsorbent is green coke.
 4. The process according to claim 2 wherein thegreen coke has an average size of between 1 and 250 microns.
 5. Theprocess according to claim 2 wherein the green coke has an average sizeof between 3 and 50 microns.
 6. The process according to claim 2 whereinthe green coke has an average size of between 5 and 25 microns.
 7. Theprocess according to claim 1 wherein the solid sorbent is a mixture ofgreen coke and recycled green coke that has been subjected to an inertheating process to liberate/pyrolizing contaminants from a previouscontaminant adsorption process.
 8. The process according to claim 7wherein the mixture of green coke and recycled green coke has an averagesize of between 1 and 250 microns.
 9. The process according to claim 7wherein the mixture of green coke and recycled green coke has an averagesize of between 3 and 50 microns.
 10. The process according to claim 6wherein the mixture of green coke and recycled green coke has an averagesize of between 5 and 25 microns.
 11. The process according to claim 1further including a step of de-wetting the solid sorbent withcontainments agglomerated thereon so as to remove any residual crude oilfrom the solid sorbent.
 12. The process according to claim 10 furtherincluding the step of heating the solid sorbent to liberate thecontaminants from the solid sorbent and to prepare the solid sorbent forrecycling for re-use as solid sorbent in the contaminant removalprocess.
 13. The process according to claim 11 further including thestep of separating undersized solid sorbent particles prior to recyclingthe solid sorbent so as to maintain a desired particle size for thesolid sorbent used in the contaminant removal process.
 14. The processaccording to claim 1 wherein the solid sorbent is selected to have adensity of between 0.5 g/cc and 7 g/cc.
 15. The process according toclaim 1 wherein the solid sorbent is selected to have a density ofbetween 0.7 g/cc and 2.0 g/cc.
 16. The process according to claim 1wherein the solid sorbent is selected to be partially or almost totallyhydrocarbon materials that contain a residual carbon content of at least40%.
 17. The process according to claim 1 wherein the solid sorbent isselected to be partially or almost totally hydrocarbon materials thatcontain a residual carbon content of between 75% and 99%.
 18. Theprocess according to claim 1 wherein the solid sorbent is selected to bepartially or almost totally hydrocarbon materials that contain aresidual carbon content of between 85% and 98%.